Cabin for a work vehicle

ABSTRACT

A cabin for a work vehicle comprises: a driver&#39;s seat positioned within the cabin; cabin frames including at least a transverse frame located in a rear region of the cabin; a roof supported by at least some of the cabin frames; at least one air-conditioning duct located within the roof an air conditioning unit located rearwardly with respect to a rearward end of a seat portion of the driver&#39;s seat and adjacent the transverse frame for conditioning air and for feeding air-conditioned air into the at least one air-conditioning duct.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of co-pending U.S. patentapplication Ser. No. 11/371,357 filed Mar. 8, 2006, which claimspriority to JP2005-251643, JP2005-251644, and JP2005-251645, each filedAug. 31, 2005.

BACKGROUND OF THE INVENTION

The present invention is directed to a cabin for a work vehicle, andmore particularly to an air conditioning unit within the cabin roof.

For arranging the air-conditioning unit, the forward half of the roof isformed as a low ceiling portion bulging downward. The air-conditioningunit is arranged in a front portion of the low ceiling portion (e.g. JPPublication No. 2005-1537 (paragraph number [0016], FIG. 1 and FIG. 2).

In the above construction, the roof includes a low ceiling portion thataccommodates the air-conditioning unit. This leads to narrowing of anupper forward field of view. Then, when performing a front loaderoperation, the driver seated on the driver's seat has difficulty inascertaining a position of the bucket near an upper position, resultingin a possibility of lowering working efficiency.

SUMMARY OF THE INVENTION

The object of this invention is to provide an air-conditioning structurefor a cab of a working vehicle with an improved upper forward view byproviding a better arrangement for the air-conditioning unit.

A cabin for a work vehicle in accordance with the present inventioncomprises: a driver's seat positioned within the cabin; cabin framesincluding at least a transverse frame located in a rear region of thecabin; a roof supported by at least some of the cabin frames; at leastone air-conditioning duct located within the roof, an air conditioningunit located rearwardly with respect to a rearward end of a seat portionof the driver's seat and adjacent the transverse frame for conditioningair and for feeding air-conditioned air into the at least oneair-conditioning duct.

Since the air-conditioning unit is disposed rearwardly with respect tothe rear end of the seat portion of the driver's seat, a low ceilingportion for accommodating the air-conditioning unit need not be formedin a front portion of the roof of the cabin. A windshield position canbe set high. As a result, an improved upper forward field of view isprovided.

Moreover, since the position of the air-conditioning unit is setrearwardly of the rear end of the seat portion of the driver's seat, alow ceiling portion formed in the rear of the roof in order toaccommodate the air-conditioning unit would not diminish the forwardfield of view of the driver seated on the driver's seat, but canalleviate a narrowing of overhead space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side elevation of a tractor;

FIG. 2 shows a perspective view showing a structural framework in afirst embodiment;

FIG. 3 shows a side view in vertical section showing a cabin interior inthe first embodiment;

FIG. 4 shows a plan view in cross section showing an inner surface of aninner roof portion seen from an outer roof in FIG. 2;

FIG. 5 shows a front view showing a duct disposed laterally of a roof;

FIG. 6 shows a perspective view showing a structural frame in a secondembodiment;

FIG. 7 shows a side view in vertical section side showing a mountingstructure for an air conditioning unit in the second embodiment;

FIG. 8 shows a perspective view showing a structural framework in athird embodiment;

FIG. 9 shows a side view in vertical section side showing a mountingstructure for an air conditioning unit in the third embodiment;

FIG. 10 shows a perspective view showing a structural framework in afourth embodiment;

FIG. 11 shows a side view in vertical section side showing a mountingstructure for an air conditioning unit in the fourth embodiment;

FIG. 12 shows a plan view in cross section showing a differentembodiment of the air conditioning duct;

FIG. 13 shows a plan view in cross section showing a differentembodiment of the air conditioning duct;

FIG. 14 shows a rear view showing an arrangement of the air conditioningduct in FIG. 13;

FIG. 15 shows Side view in vertical section side showing an upper frameserving also as a duct;

FIG. 16 (A) shows a perspective view showing upper ends of front postshigher than fore and aft frames;

FIG. 16 (B) shows a principle view showing an upper forward field ofview for the driver in FIG. 16 (A);

FIG. 17 (A) shows a perspective view showing upper ends of front postsarranged rearwardly of front forward ends of fore and aft frames;

FIG. 17 (B) shows a perspective view showing an upper forward field ofview for the driver in FIG. 17 (A); and

FIG. 18 shows a plan view in cross section showing an inner surface ofan inner roof portion seen from outside the roof.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

While several embodiments will be described below, a combination of afeature in one embodiment with another in a different embodiment isunderstood to be within the scope of the present invention unless suchcombination leads to a contradiction.

An agricultural tractor will be described as an example of themaintenance vehicle. As shown in FIGS. 1 and 2, the agricultural tractorhas a cab 1 formed of vertical frames 2 of a structural framework Bconstituting a framework, boarding and alighting side doors 3, rear sidewindows 4 and a rear window 5 having transparent glass planes coveringportions surrounded by the vertical frames 2, an annular upper frame 6extending over upper surfaces of the vertical frames 2, and a roof 7placed on the upper frame 6.

The cabin 1 defines a driving and control section 8 therein. The drivingand control section 8 includes a steering wheel 11 attached to asteering column 10 disposed adjacent an engine hood 9, and a driver'sseat 12 disposed rearwardly of the steering column 10. The rearward endof the seating portion of the driver's seat 12 means a rear end of thetop surface where the driver sits. When the seat 12 has a seat padportion and a separate seat back, the rearward end of the seatingportion of the driver's seat 12 may mean the rearward end of the seatpad portion.

The roof 7 supports an air-conditioning unit A for air-conditioning theinterior of the cab 1.

First Embodiment

Different forms of attaching the air-conditioning unit A will bedescribed hereinafter. A first embodiment will be described first, inwhich, as shown in FIGS. 2 and 3, the air-conditioning unit A is mountedabove a rear end of the annular upper frame 6 extending over the uppersurfaces of the vertical frames 2 constituting the structural frameworkB. A rear frame portion 6B located in a rear position of a hood portion7 of the annular upper frame 6 is called a transverse frame herein.

The construction of the structural framework B for supporting theair-conditioning unit A will be described. As shown in FIG. 2, right andleft vertical frames 2 are erected at connecting bend portions betweenfore and aft frame portions 6A and rear frame portion 6B acting as thetransverse frame of the annular upper frame 6, to serve also as windowframes of the rear side windows 4. A support frame 6C is laid to extendbetween the two vertical frames 2 and at a height level a step lowerthan the rear frame portion 6B.

The air-conditioning unit A is placed in a state of being dropped on theupper surface of the support frame 6C and between the neighboringvertical frames 2 supporting the support frame 6C. The support frame 6Cis called herein an air-conditioning unit mounting portion.

As shown in FIG. 3, a pair of right and left brackets 16 are attached ina fore and aft posture to the upper surface of the support frame 6C. Theair-conditioning unit A enclosed in a unit case 24 is placed on andfixed by bolts to the right and left brackets 16.

The construction of the roof 7 will be described.

As shown in FIGS. 3 through 5, the roof 7 includes an outer roof 13 andan inner roof 14, each attached to and supported by the upper frame 6.The inner roof 14 is an integral resin molding article, has a rearwardhalf thereof above the driver's seat 12 formed as a low ceiling portionbulging downward. The air-conditioning unit A is mounted in this lowceiling portion.

As shown in FIGS. 2 and 3, the outer roof 13 is laid on the uppersurface of the upper frame 6, and is in the form of a flat plate largerthan the support surface. A seal ring 19 of rectangular section formedin the shape of a ring is attached to a downward-facing surface of theouter roof 13. In the state of the outer roof 13 laid on the upper frame6, part of the section of the seal ring 19 contacts the upper surface ofthe upper frame 6, to stop circulation of air to and from the exterior.

As shown in FIGS. 3 through 5, ambient air intake openings 13B areformed in downward surfaces of sideways eaves portions 13E of the outerroof 13 projecting from opposite sides of the upper frame 6. An ambientair feed opening 13C communicating with the above ambient air intakeopenings 13B is formed in a position inwardly of the seal ring 19.Numeral 33 in the drawings denotes dust filters provided for the ambientair intake openings 13B.

Air drawn in through the ambient air intake openings 13B is guidedforwardly of the vehicle body through a communicating path “b” acting asan ambient air feed duct formed in the double wall of the outer roof 13,and is blown off from the ambient air feed opening 13C formed forwardlyof the communicating path “b” into a space “a” leading to theair-conditioning unit A described hereinafter.

The internal structure of the inner roof 14 will be described. As shownin FIGS. 1 through 4, the air-conditioning unit A includes an evaporator20, and a heater 21 disposed forwardly thereof. The evaporator 20cooperates with a compressor, an expansion valve and a condenser toconstitute a coolant circulation circuit. The heater 21 is connectedthrough piping to a radiator 22 mounted in the engine hood 9.

A sirocco fan 23 is disposed at the right-hand side of the evaporator 20for feeding the ambient air drawn in through the ambient air feedopening 13C toward the evaporator 20 and heater 21.

As shown in FIG. 3, the ambient air introduced through the ambient airfeed opening 13C, is drawn and guided through the space “a” formedbetween the downward surface of the outer roof 13 and the inner roof 14acting as a circulation path, to a guide bore 24 a of the sirocco fan 23enclosed in the unit case 24.

As shown in FIGS. 3 and 4, the evaporator 20 and sirocco fan 23 aresurrounded by the unit case 24. A rear air-conditioning duct 15Acontinuous with the unit case 24 extends transversely for guidingconditioning air from the air-conditioning unit A, from opposite lateralends of the evaporator 20 to the right and left sides. Lateralair-conditioning ducts 15B extend forward from opposite lateral ends ofthe rear air-conditioning duct 15A for guiding the conditioning airforwardly of the vehicle body.

The right and left air-conditioning ducts 15B and 15B will be described.As shown in FIGS. 3 through 5, each of the right and leftair-conditioning ducts 15B has inwardly directed blow-off openings 15 b,and the rearward blow-off opening 15 b is located for directing anappropriate amount of cool air near the driver's face. On the otherhand, each lateral air-conditioning duct 15B has blow-off openings 15 aarranged adjacent the forward thereof and directed forward and downwardfor blowing off the conditioning air toward a windshield 25 of the cab1, and a blow-off opening 15 d disposed rearwardly of the blow-offopenings 15 a for blowing off defrost air toward the door glass.

As shown in FIGS. 2 and 3, branch ducts 15C extend rearward from theopposite ends of the rear air-conditioning duct 15A, and blow-offopenings 15 c are formed at extension ends thereof for blowing off theconditioning air to the rear side windows 4 and rear window 5. The abovelateral air-conditioning ducts 15B and the like are located in the innerroof 14, and are mounted in low ceiling portions formed at oppositesides of the inner roof 14 as shown in FIG. 5.

As shown in FIG. 3, the inner roof 14 includes a circulation opening 14Adisposed forwardly of the portion accommodating the air-conditioningunit A for drawing in air of the cab interior. A wall surface extendsupward along the unit case 24 from an upper surface of a slope of abottom inner roof 14 b defining the low ceiling portion, and thecirculation opening 14A is formed in a horizontal portion at the upperend of the vertical surface 14 c. The vertical surface 14 c of the topinner roof 14 a is called herein an interior air introducing duct.

On the other hand, the ambient air feed opening 13C and circulationopening 14A are vertically opposed to each other, and a switching valve17 is disposed therebetween to act as a valve mechanism for opening andclosing the ambient air feed opening 13C and circulation opening 14A.Thus, a switching is made between a state of drawing ambient air throughthe ambient air intake openings 13B into the space “a” formed betweenthe inner roof 14 and outer roof 13, and a state of shutting off ambientair and circulating the air in the cab interior through the space “a”.

The valve mechanism may be the slide type rather than the pivoting type.Although not shown, the valve mechanism is operable by a switching levererected to a level above and adjacent the driver's seat 12.

As shown in FIG. 3, the inner roof 14, which has the circulation opening14A for drawing in air of the cab interior, includes a rear top innerroof portion 14 a defining the circulation opening 14A, and a forwardinner roof portion 14 b located in the forward part of the cab 1. Theinner roof 14 has a fore and aft intermediate position thereof in tightcontact with the outer roof 13. The intermediate position in tightcontact separates the rear inner roof portion 14 a and forward innerroof portion 14 b. A CD radio cassette recorder 29 or the like ismounted in a space of the forward inner roof portion 14 b having theabove construction. The back pressure of the interior air taken in fromthe circulation opening 14A does not directly act on the CD radiocassette recorder 29 or the like, so that the CD radio cassette recorder29 or the like has a reduced chance of drawing in dust and the like.

As shown in FIGS. 3 through 5, the ambient air intake openings 13B arearranged adjacent the air conditioning unit A. Consequently, thecommunicating path b formed in the outer roof portion 13 andcommunicating with the ambient air intake openings 13B may be shortened,and the sirocco fan 23 may have a reduced suction resistance.

A support cover 18 extends rearwardly of the support frame 6C forcovering the air conditioning unit A. The rear window 5 is supported bythe support frame 6C and on the undersurface of the support cover 18 tobe pivotable rearward about a transverse axis X. In a closed state, therear window 5 does not protrude a large extent rearward, thereby toavoid interference with a linkage mechanism and the like supporting atilling implement, though these components are not shown in thedrawings.

Second Embodiment

Next, a second embodiment will be described, in which, as shown in FIG.6, the air-conditioning unit A is mounted forwardly of the rear end ofthe annular upper frame 6.

As shown in FIGS. 6 and 7, an outer roof 13 and an inner roof 14 arearranged to surround the air-conditioning unit A. An ambient air feedopening 13C is formed in the outer roof 13 forwardly of theair-conditioning unit A, and an ambient air intake opening 13B is formedin a downward surface of an eaves portion 13A of the outer roof 13projecting rearwardly for feeding ambient air to the ambient air feedopening 13C. The inner roof 14 has a circulation opening 14A opposed tothe ambient air feed opening 13C for drawing in air from the interior ofthe cab 1. A switching valve 17 is disposed between the ambient air feedopening 13C and circulation opening 14A to act as a valve mechanism foropening and closing the ambient air feed opening 13C and circulationopening 14A. A switching may be made between a state of drawing ambientair through the ambient air intake opening 13B into a space “a” formedbetween the inner roof 14 and outer roof 13, and a state of shutting offambient air and circulating the air in the cab interior through thespace “a”.

Air taken into the space “a” is drawn into the sirocco fan 23 via aguide bore 24 a formed in the upper surface of the unit case 24 of theair-conditioning unit A. After being conditioned by the evaporator 20and the like, the air is delivered to the air-conditioning ducts 15A and15B.

As shown in FIG. 4, the rear air-conditioning duct 15A extends fromopposite lateral ends of the evaporator 20 as described hereinbefore,and lateral air-conditioning ducts 15B extend forward from oppositelateral ends of the rear air-conditioning duct 15A for blowing offconditioning air into the cab as in the first embodiment.

Next, a mounting structure for the rear side windows 4 and rear window 5will be described. FIG. 7 shows the air-conditioning unit A disposedforwardly of the rear end of the annular upper frame 6. In order toemploy the construction for arranging the air-conditioning unit Aforwardly of the rear end of the annular upper frame 6, the rear end ofthe annular upper frame 6 is displaced rearwardly of the position of therear window 5. For this reason, rear pillars acting as the verticalframes 2 located at boundaries between the rear window 5 and rear sidewindows 4 are connected to the upper frame 6 through connecting frames30 to increase connecting strength of the frames. The rear window 5 issupported, to be pivotable rearward to an open position, by pivot arms32 pivotally connected to brackets 31 attached to the rear frame portion6B of the upper frame 6.

Third Embodiment

Next, a third embodiment will be described, in which, as shown in FIG.8, the air-conditioning unit A is mounted below a suspending frameportion 6D formed on the rear frame portion 6B acting as the transverseframe.

The construction of the structural framework B for supporting theair-conditioning unit A will be described. As shown in FIGS. 8 and 9,right and left vertical frames 2 are erected at connecting bend portionsbetween fore and aft frame portions 6A and rear frame portion 6B of theannular upper frame 6, to serve also as window frames of the rear sidewindows 4. The suspending frame portion 6D is laid to extend between thetwo vertical frames 2 and at a height level a step higher than the rearframe portion 6B.

The air-conditioning unit A is suspended in a state of being slippedunder the lower surface of the suspending frame portion 6D and betweenthe neighboring vertical frames 2 supporting the suspending frameportion 6D. The suspending frame portion 6D is called herein anair-conditioning unit mounting portion.

As shown in FIG. 9, a pair of right and left brackets 27 are attached ina fore and aft posture to the lower surface of the suspending frameportion 6D. The air-conditioning unit A enclosed in a unit case 24 isfixed by bolts to the right and left brackets 27.

As shown in FIG. 9, an outer roof 13 and an inner roof 14 are arrangedto surround the air-conditioning unit A. An ambient air feed opening 13Cis formed in the outer roof 13 forwardly of the air-conditioning unit A,and ambient air intake openings (not shown) are formed in eaves portions(not shown) of the outer roof 13 projecting laterally of the vehiclebody for feeding ambient air to the ambient air feed opening 13C. Theinner roof 14 has a circulation opening 14A opposed to the ambient airfeed opening 13C for drawing in air from the interior of the cab 1. Aswitching valve 17 is disposed between the ambient air feed opening 13Cand circulation opening 14A to act as a valve mechanism for opening andclosing the ambient air feed opening 13C and circulation opening 14A. Aswitching may be made between a state of drawing ambient air through theambient air intake opening 13B into a space “a” formed between the innerroof 14 and outer roof 13, and a state of shutting off ambient air andcirculating the air in the cab interior through the space “a”.

Air taken into the space “a” is drawn into the sirocco fan 23 via aguide bore (not shown) formed in the upper surface of the unit case 24of the air-conditioning unit A. After being conditioned by theevaporator 20 and the like, the air is delivered to the air-conditioningducts 15A and 15B.

As shown in FIG. 4, the rear air-conditioning duct 15A extends fromopposite lateral ends of the evaporator 20 as described hereinbefore,and lateral air-conditioning ducts 15B extend forward from oppositelateral ends of the rear air-conditioning duct 15A for blowing offconditioning air into the cab as in the second embodiment.

As shown in FIG. 9, the rear window 5 is supported by the undersurfaceof a portion of the inner roof 14 projecting rearwardly of the verticalframes 2. The rear window 5 does not protrude a large extent rearward,thereby to avoid interference with a linkage mechanism and the likesupporting a tilling implement, though these components are not shown inthe drawings.

Fourth Embodiment

Next, a fourth embodiment will be described, in which, as shown in FIG.10, the air-conditioning unit A is mounted further rearwardly of therear frame portion 6B acting as the transverse frame.

The construction of the structural framework B for supporting theair-conditioning unit A will be described. As shown in FIGS. 10 and 11,right and left vertical frames 2 are erected at connecting bend portionsbetween fore and aft frame portions 6A and rear frame portion 6B of theannular upper frame 6, to serve also as window frames of the rear sidewindows 4.

As shown in FIG. 11, a pair of right and left brackets 27 are attachedin a fore and aft posture to the lower surface of the rear frame portion6B. The air-conditioning unit A enclosed in the unit case 24 is fixed bybolts to the right and left brackets 27.

As shown in FIG. 11, a rear cover 28 is attached to the rear frameportion 6B to surround the air-conditioning unit A attached to the rearframe portion 6B. The outer roof 13 is supported by the rear frameportion 6B, and the inner roof 14 is supported by the rear cover 28.

An ambient air feed opening 13C is formed in the outer roof 13, andambient air intake openings (not shown) are formed in eaves portions(not shown) of the outer roof 13 projecting laterally of the vehiclebody for feeding ambient air to the ambient air feed opening 13C. Theinner roof 14 has a circulation opening 14A opposed to the ambient airfeed opening 13C for drawing in air from the interior of the cab 1. Aswitching valve 17 is disposed between the ambient air feed opening 13Cand circulation opening 14A to act as a valve mechanism for opening andclosing the ambient air feed opening 13C and circulation opening 14A.The switching valve 17 switches between a state of drawing ambient airintroduced through the ambient air intake opening 13B, via a spacebetween the inner roof 14 and outer roof 28, into an inner space “a” ofthe rear cover 28, and a state of shutting off ambient air andcirculating the air in the cab interior through the inner space “a”.Reference “b” in the drawing denotes an ambient intake guide, and 14 cdenotes an interior air intake guide.

Air taken into the space “a” is drawn into the sirocco fan 23 via aguide bore 24 a formed in the upper surface of the unit case 24 of theair-conditioning unit A. After being conditioned by the evaporator 20and the like, the air is delivered to the air-conditioning ducts 15A and15B.

As shown in FIG. 4, the rear air-conditioning duct 15A is disposedforwardly of the evaporator 20, and lateral air-conditioning ducts 15Bextend forward from opposite lateral ends of the rear air-conditioningduct 15A for blowing off conditioning air into the cab as in the firstto third embodiments.

The rear window 5 is supported by an undersurface of a connectionbetween the inner roof 14 and rear cover 28. The rear window 5 does notprotrude a large extent rearward, thereby to avoid interference with alinkage mechanism and the like supporting a tilling implement, thoughthese components are not shown in the drawings.

Other Embodiments

The following modified constructions should be understood as applicableto the first to fourth embodiments described hereinbefore.

(1) A modified construction of the air-conditioning duct 15 will bedescribed. A construction in which ducts 15 are arranged in the cab 1and in a transversely middle position of the roof 7 will be describedhere. As shown in FIG. 12, an evaporator 20 and a sirocco fan 23 aresurrounded by a unit case 24. A rear air-conditioning duct 15Acontinuous with the unit case 24 extends transversely for guidingconditioned air from the air-conditioning unit A, from opposite lateralends of the evaporator 20 to the right and left sides. A centralair-conditioning duct 15E acting as a main air-conditioning duct extendsforward from a transversely middle portion of the rear air-conditioningduct 15A for guiding the conditioned air forwardly of the vehicle body.

As shown in FIG. 12, the central air-conditioning duct 15E include rightand left intermediate branch air-conditioning ducts 15F acting as branchair-conditioning ducts extending right and left from intermediatepositions in the fore and aft direction, and front air-conditioningducts 15G extending to full extents right and left from positionsforwardly of the intermediate branch air-conditioning ducts 15F. Each ofthe right and left intermediate branch air-conditioning ducts 15F hasblow-off openings 15 f formed therein. The blow-off openings 15 f arelocated to blow off an appropriate quantity of cool air to near thedriver's face. On the other hand, the front air-conditioning ducts 15Ghave front blow-off openings 15 a formed therein for blowing offconditioning air forward and downward toward the windshield 25 of thecab 1, and blow-off openings 15 d formed rearwardly of the frontblow-off openings 15 a for blowing off defrost air toward the door glasspanes.

As shown in FIG. 12, branch ducts 15C extend rearward from oppositelateral ends of the rear air-conditioning duct 15A, and have blow-offopenings 15 c formed therein for blowing conditioning air to the rearside windows 4 and rear window 5.

(2) A different modified construction of the air-conditioning duct 15will be described. In this construction, the duct 15 is arranged in thecab 1 to cover the entire surface of the roof 7. As shown in FIGS. 13and 14, an evaporator 20 and a sirocco fan 23 are surrounded by a unitcase 24. A full surface air-conditioning duct 1511 continuous with theunit case 24 extends forward from opposite lateral ends of theevaporator 20 for guiding conditioned air forward from theair-conditioning unit A.

As shown in FIG. 13, the full surface air-conditioning duct 1511 hasblow-off openings 15 f formed in intermediate positions in the fore andaft direction. The blow-off openings 15 f are located to blow off anappropriate quantity of cool air rearward to near the driver's face. Onthe other hand, blow-off openings 15 a are formed in the cab 1 forblowing off conditioning air forward and downward toward the windshield25 of the cab 1. Blow-off openings 15 d are formed rearwardly of thefront blow-off openings 15 a for blowing off defrost air toward the doorglass panes.

As shown in FIG. 13, the full surface air-conditioning duct 1511 hasblow-off openings 15 b formed therein for blowing conditioning air tothe rear side windows 4 and rear window 5. The air-conditioning duct 15covering substantially the entire surface as described above has anadvantage of allowing the blow-off openings to be formed in desiredpositions.

As a structure for introduces external air into the full surface duct15H having such construction, as shown in FIGS. 13 and 14, ambient airfeed openings 13B are formed in eaves portion 13E of the outer roof 13projecting laterally of the vehicle body.

(3) Although not shown, bellows-like connectors may be provided in theconnections between the right and left air-conditioning ducts 15B and15B and rear air-conditioning duct 15A. Then, the connecting state isstabilized by the elasticity of the duct itself and by absorbingmanufacturing errors, for example.

(4) As shown in FIG. 13, a hose 26 extends from the unit case 24 todischarge dew water from the evaporator 20. The hose 26 extends out ofthe vehicle body through the interior of the vertical frame 2 presentadjacent the unit case 24.

(5) A mode of using the upper frame 6 as air-conditioning ducts 15 willbe described next. As shown in FIG. 15, an ambient air intake opening(not shown) is formed in a rearward eaves portion (not shown) of theouter roof 13. Air is taken in from a communicating path “b” of theouter roof 13 into a space “a” formed with the inner roof 14, andintroduced through a guide bore 24 a into the air-conditioning unit A.As shown in FIG. 15, ambient air and interior air introduced are sentout of an exit 24A of the unit case 24 after being adjusted by theair-conditioning unit A. The exit 24A communicates with the interiorspace of the upper frame 6, so that the fore and aft frame portions 6Aof the upper frame 6 serve as the air-conditioning ducts 15.

Thus, as shown in FIG. 15, air blow-off openings 6 a of conditioned airare formed in inner surfaces of the fore and aft frame portions 6A.Since the upper frame 6 is used also as air-conditioning ducts, there isno need to provide air-conditioning ducts separately.

The mode of supporting the air-conditioning unit A is the same as in thefirst embodiment.

(6) The following framework construction may be adopted for the cab 1.As shown in FIG. 16 (A), (B), right and left front struts 2, supportingthe windshield 25, of the structural framework B project above the rightand left, fore and aft frame portions 6A of the upper frame 6, and anupper front frame portion 6E extending transversely and connecting upperends of the front struts 2 is installed above the right and left, foreand aft frame portions 6A. Since these components are located above theright and left, fore and aft frame portions 6A, the windshield 25 may belocated in a correspondingly elevated position, to provide an excellent,enlarged field of view for the driver.

As shown in FIG. 17 (A), (B), right and left front struts 2 are curvedso that upper end regions 2A are located further rearward than lowerregions of the front struts 2. An upper front frame portion 6E is placedto extend between the upper ends of the front struts 2. The upper frontframe portion 6E and the right and left, fore and aft frame portions 6Aare set to the same height.

With this construction, the upper front frame portion 6E can be locatedfurther rearward than the lower regions of the front struts 2. Thedriver can look up with an enlarged field of view, to be able to see anincreased height.

(7) The outer roof 13 may have eaves portions projecting laterally orfore and aft from the upper frame 6, to prevent direct rays entering thecab having large glass surfaces.

(8) The foregoing embodiments have been described as applying thisinvention to the agricultural tractor. The invention may be applied toother agricultural machines such as a combine or to constructionequipment.

(9) A lateral air-conditioning duct 15B may be provided for only one ofthe right and left sides.

(10) The ambient air intake opening 13B may be provided only to one ofthe eaves portions 13E, as shown in FIG. 18. Especially when it isprovided on the left side (i.e. the side the operator often gets in andout of the cabin) of the roof (7), the filter in the ambient air intakeopening 13B may more easily be accessed for checking and maintenance.Also, since the fan 23 is located on the right hand area of the roof 7,the air flow speed can be increased due to funneling effect since theopening 13B is located at a distance from the fan 23, leading to anincreased efficiency of the fan 23.

1. A cabin of a work vehicle having an air conditioning unit, the cabincomprising: a roof (7) of the cabin (1); and the air conditioning unit(A) arranged in a rear portion of the roof (7), wherein the roof (7)comprises: a hollow outer roof (13) having an ambient air intake opening(13B) for introducing an ambient air to a hollow of the outer roof (13),and an ambient air feed opening (13C) formed in a lower face of theouter roof (13) for allowing the hollow to communicate with the airconditioning unit (A); and an inner roof (14) disposed under the lowerface of the outer roof (13) to form a space therebetween, in which spacethe air conditioning unit (A) is disposed, an air conditioning duct (15)comprising separate right and left lateral air conditioning ducts (15B,15B) is located frontwardly with respect to the air conditioning unit(A) and in right and left lateral regions of the roof (7), whichbranches from the air conditioning unit (A) and extends to andterminates at the front portion of the roof having a windshield (25),the right and left lateral air-conditioning ducts (15B, 15B) beingdisposed in the space between the outer roof (13) and the inner roof(14) so that a secondary space is formed between an inner face of thespace and an outer face of the air-conditioning duct (15B), and whereineach lateral air conditioning duct (15B) comprises: a front terminalwhich is provided in the front side of the roof (7) and serves aterminal of an air path in the air conditioning duct (15B); a bent ductportion on a front end portion thereof, which is bent inward withrespect to a vehicle body; a first blow-off opening (15 a) formed in afront end portion of the bent duct portion, which opening is directeddownward for blowing off conditioned air toward the windshield (25) ofthe cabin (1); and a second blow-off opening (15 a) formed in a bentportion between the bent duct portion and the remaining portionextending in a front-rear direction, which opening is directed downward,the left bent duct portion comprises a linear portion extendingdiagonally forward right toward a front right side of the vehicle bodywhen viewed from above, and the right bent duct portion comprises alinear portion extending diagonally forward left toward a front leftside of the vehicle body when viewed from above.
 2. The cabin of a workvehicle according to claim 1, wherein the cabin (1) comprises astructural framework (B) which defines a front half space of the cabinas an approximate cuboid and includes a right and left front verticalframes defining a front face of the cabin (1), and the second blow-offopenings (15 a) are located in the vicinity of respective front verticalframes.
 3. A cabin of a work vehicle having an air conditioning unit,the cabin comprising: a roof (7) of the cabin (1); and the airconditioning unit (A) which is arranged in a rear portion of the roof(7) and comprises an evaporator (20), a heater (21) and a fan (23) forsupplying air to the evaporator (20) and the heater (21), wherein theroof (7) comprises: a hollow outer roof (13) having an ambient airintake opening (13B) for introducing an ambient air to a hollow of theouter roof (13), and an ambient air feed opening (13C) formed in a lowerface of the outer roof (13) for allowing the hollow to communicate withthe air conditioning unit (A); and an inner roof (14) disposed under thelower face of the outer roof (13) to form a space therebetween, in whichspace the air conditioning unit (A) is disposed, the ambient air intakeopening (13B) is provided in the outer roof (13) on only one of lateralsides of the cabin (1), and the fan (23) is located on one of thelateral sides opposite to the lateral side on which the ambient airintake opening (13B) is provided.
 4. The cabin of a work vehicleaccording to claim 3, wherein an eaves portion (13E) is provided to eachof the lateral sides of the outer roof (13), and the ambient air intakeopening (13B) is formed in a lower face of only one of the eaves portion(13E).
 5. The cabin of a work vehicle according to claim 4, wherein theair conditioning unit (A) is mounted so that a rear end thereof ispositioned rearward of a rear window (5) of the cabin (1), the outerroof (13) of the roof (7) extends rearward of the rear window (5) so asto cover an upper portion of the air conditioning unit (A), the eavesportions (13E) extend rearward so that extended portions thereof arelocated on both lateral sides of an extended portion of the outer roof(13), and the ambient air intake opening (13B) extends rearward so thatan extended portion thereof is adjacent to the extended portion of theouter roof (13).
 6. A cabin of a work vehicle having an air conditioningunit, the cabin comprising: a driver's seat (12) positioned within thecabin (1); a roof (7); an air conditioning duct (15) located inside theroof (7); the air conditioning unit (A) located inside the roof (7) forconditioning air and for feeding air conditioned air into the airconditioning duct (15); and a structural framework (B), wherein the airconditioning unit (A) is located rearward of a rearward end of a seatportion of the driver's seat (12), the air conditioning unit (A)comprises a ventilating fan (23), an evaporator (20), and a heater (21),the ventilating fan (23) being located in one of right and left handside regions of a vehicle body, the evaporator (20) and the heater (21)being located on the other of the right and left hand side regions ofthe vehicle body such that the evaporator (20) and the heater (21) arepositioned next to each other in the fore-and-aft direction and rearwardof a front end of the ventilating fan (23), the structural frame (B)includes a plurality of vertical frames (2), and an upper frame (6)spanning top end portions of the vertical frames (2) and comprising: atransverse frame (6B) located at a rear portion of the roof (7); andright and left fore-and-aft frames (6A), the transverse frame (6B)extends between the vertical frames (2) located on both lateral sides ofthe transverse frame (6B), the transverse frame (6B) extending at aheight level lower than the fore-and-aft frames (6A), and a lowerportion of the air conditioning unit (A) is mounted on an upper face ofa bracket (16) fixed to the transverse frame (6B) so that the airconditioning unit (A) is placed between the vertical frames (2) locatedon both sides of the transverse frame (6B) when viewed from above.